Platinum-Catalyzed Allylic C-H Alkylation with Malononitriles

Abstract

The direct functionalization of allylic C-H bonds is distinguished by enabling rapid assembly of structural complexity from simple molecules. Although Pd-catalyzed allylic C-H functionalization has been extensively studied, the discovery of new catalytic systems remains fairly underdeveloped. Here, we disclose a Pt-catalyzed allylic C-H alkylation of a wide range of α-alkenes by using phosphoramidites as ligands and malononitriles as alkylating reagents. Notably, the combination of chiral urea-catalyzed Michael addition and Pt-catalyzed allylic C-H alkylation can serve as an efficient protocol to access chiral tetrahydropyran with high levels of diastereo- and enantioselectivity. Mechanistic studies suggest that the Pt-catalyzed allylic C-H activation proceeds through a concerted proton and two-electron transfer process, which is analogous to transition state geometries of Pd catalysis.